I am starting a nonprofit organization for refugees. Is there a national Articles of Incorporation form to file, or would I have to fill one out for each state?
There is no national form of Articles of Incorporation that has to be filed in each state. You will incorporate in one state, probably the state in which your principal place of business will be located, and follow the procedure under its state law applicable to nonprofit corporations. Internal Revenue Service Publication 557 can help you with the “magic language” that is necessary if you intend to file for recognition of 501(c)(3) charitable exempt status. (See also Ready Reference Page: “Articles of Incorporation Establish Basic Form of Nonprofit Corporations”)
If you intend to solicit charitable contributions nationally, you will have to register in 39 states and the District of Columbia before you can solicit within their jurisdictions. Most of those jurisdictions accept the Unified Registration Statement, but several states have recently abandoned it in favor of their own online registration process.